CONTROL
24
4.8.1.2 Component control during oil return operation in heating and DHW modes.
Component
Refer to wiring
diagram
Control functions and states
DC inverter compressor COMP Runs at oil return operation rotation speed
Fan FAN Controlled according to heating mode
Electronic expansion valve EXV 304 (steps)
4-way valve STF*/STF1** On
* Single-phase version
** Three-phase version
4.8.2 Defrosting
In order to recover heating capacity, the defrosting operation is carried out when the unit’s air side heat exchanger is
performing as an evaporator.
The defrosting operation is controlled according to outdoor ambient temperature, air side heat exchanger refrigerant
outlet temperature and the compressor operating time.
Inlet conditions:
• T3<0°C
• T4<-2...-10 (according to water outlet temperature and permanence in these conditions).
Outlet conditions:
• after 10 minutes of defrosting cycle
• T3>8°C
Component
Refer to wiring
diagram
Control functions and states
DC inverter compressor COMP Runs at defrosting operation rotation speed
Fan FAN O
Electronic expansion valve EXV Fully open (480 steps)
4-way valve STF*/STF1** O
* Single-phase version
** Three-phase version
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